Refinancings Plunge as Bond Yields Rise

A surprise spike in mortgage rates threatens to halt a refinancing boom that has delivered strong profits for U.S. banks over the past two years.

The average rate on a 30-year mortgage rose to 4.15% last week, a 14-month high and up sharply from 3.59% in early May, according to the Mortgage Bankers Association. A separate survey released Thursday...